Vertical Piles Research Articles

Ice Specimen Retrieval and Coring Method for Accreted Ice on Vertical Piles Subjected to Tidal Changes

Ice Specimen Retrieval and Coring Method for Accreted Ice on Vertical Piles Subjected to Tidal Changes

Group interaction effect on breaking wave forces on a vertical pile: Experimental tests and predictive models

Pile groups are extensively utilized as supports for many coastal structures, such as bridges, jetties, and oil production platforms. The problem of understanding the interaction effects within pile groups and predicting the breaking wave forces on them is considered in this paper, using experimental tests and machine learning-based predictive modeling. The restriction of previous studies on this important engineering problem is that the pile group arrangements considered are limited. Prediction methods are therefore developed only for specific pile group arrangements and do not incorporate the effect of the incident wave direction. In this study, to partially overcome this limitation, an extensive experimental investigation is conducted on 70 different pile group arrangements under six breaking wave conditions. Three pile group coefficients, characterized by the total, quasi-static, and dynamic forces, are introduced for a thorough assessment of the interaction effects within the pile group. First, the pile group coefficients for three basic arrangements (tandem, side-by-side, and staggered) are evaluated. The results reveal a sheltering effect in the tandem arrangement and an amplification effect in the side-by-side arrangement. However, the forces on the measured pile in the staggered arrangement resemble those on the isolated pile, with neither significant sheltering nor amplification effects observed. Then, the results for all arrangements highlight the significant effect of wave direction on the pile group coefficients for small inter-pile spacing. Finally, different machine learning algorithms are adopted to develop predictive models for the group coefficients. The XGBoost model demonstrates superior accuracy for predicting the total and quasi-static force coefficients, while the dynamic force coefficient remains challenging to predict accurately due to its stochastic nature.

Seismic Performance of Pile Groups under Liquefaction-Induced Lateral Spreading: Insights from Advanced Numerical Modeling

Post-earthquake investigations have shown that piles in liquefiable soils are highly susceptible to damage, especially in sloping sites. This study examines the seismic performance of pile groups with lateral spreading through advanced numerical modeling. A three-dimensional finite element model, validated against large-scale shaking table test results, is implemented to capture the key mechanisms driving the dynamic response of pile groups under both inertial and kinematic loading conditions. Parametric seismic response analyses are conducted to compare the behavior of batter and vertical piles under varying ground motion intensities. The results indicate that batter piles experience increased axial compressive and tensile forces compared to vertical piles, up to 70% and 20%, respectively. However, batter piles provide enhanced lateral stiffness and shear resistance compared to vertical piles, reducing horizontal displacements by up to 20% and tilting the cap by 85% under strong ground motion. The results demonstrate that batter piles not only enhance the overall seismic stability of the structure but also mitigate the risk of liquefaction-induced lateral spreading in the near-field through pile-pinning effects. While vertical piles are more commonly used in practice, the distinct advantages of batter piles for seismic stability highlighted in this study may encourage using more advanced numerical modeling in engineering projects.

Response of Batter Piles Subjected to Static and Seismic Loading: Review Study

Battered piles are beneficial when used as foundations where significant lateral resistance is required, which could result from extreme water waves, winds, soil pressures, massive hits of explosions, or earthquakes. Experimental and numerical research must focus on that direction to reveal how these foundations behave under different loading conditions. The present study reviews the investigations conducted on the performance of batter pile foundations and attempts to understand and cover various aspects related to this issue; after conducting the review, the results indicate that the negative battered piles provide an efficient lateral stiffness corresponding to positive battered piles and a vertical one. Also, lateral bearing capacity improved with the inclusion of battered piles. Moreover, batter piles respond better than vertical piles in liquefiable soil under seismic excitation. The current study also showed that the pullout capacity of batter piles increased with the batter angle.

Effect of combined lateral and uplift loads on vertical and batter pile groups in cohesion less soil

Effect of combined lateral and uplift loads on vertical and batter pile groups in cohesion less soil

Investigation of flow over an inclination pile under a Reynolds number of 3900 by numerical simulation

Flow over an inclination pile was studied numerically by solving the Navier–Stokes equations with large eddy simulation closure under a Reynolds number of 3900, and the inclination angles were in the range of −45° ≤ θ ≤ 45°. First, flow over a finite-length vertical pile with symmetric boundary conditions at both the upper and lower boundaries is used for verification, and the results are in good agreement with the previous results. Then, the lower boundary is set as a no-slip wall to simulate a rigid seabed, and 19 different inclination angles are numerically simulated to investigate the effects of the rigid seabed on the hydrodynamic characteristics and the wake structure of the cylindrical wake with different inclination angles. It is found that there is a significant difference between the forces on the piles, which were inclined forward and backward due to the end boundary conditions. When the pile is inclined forward, the force on the pile and the frequency of vortex shedding are lower than that of a vertical pile, which is more conducive to the stability of the structure. When the pile is inclined backward, the lower sidewall induces a strong spiral upward flow of the fluid at the lower end around the pile, which leads to the shedding of the wake vortex at a very close position to the pile. The return zone tightening phenomenon occurs at inclination angles greater than 25° backward, and this phenomenon leads to a sharp increase in the forces on the pile. Backward inclination angles greater than 30° are extremely unfavorable for structural forces.

Numerical Simulation and Deformation Prediction of Deep Pit Based on PSO-BP Neural Network Inversion of Soil Parameters.

The finite element numerical simulation results of deep pit deformation are greatly influenced by soil layer parameters, which are crucial in determining the accuracy of deformation prediction results. This study employs the orthogonal experimental design to determine the combinations of various soil layer parameters in deep pits. Displacement values at specific measurement points were calculated using PLAXIS 3D under these varying parameter combinations to generate training samples. The nonlinear mapping ability of the Back Propagation (BP) neural network and Particle Swarm Optimization (PSO) were used for sample global optimization. Combining these with actual onsite measurements, we inversely calculate soil layer parameter values to update the input parameters for PLAXIS 3D. This allows us to conduct dynamic deformation prediction studies throughout the entire excavation process of deep pits. The results indicate that the use of the PSO-BP neural network for inverting soil layer parameters effectively enhances the convergence speed of the BP neural network model and avoids the issue of easily falling into local optimal solutions. The use of PLAXIS 3D to simulate the excavation process of the pit accurately reflects the dynamic changes in the displacement of the retaining structure, and the numerical simulation results show good agreement with the measured values. By updating the model parameters in real-time and calculating the pile displacement under different working conditions, the absolute errors between the measured and simulated values of pile top vertical displacement and pile body maximum horizontal displacement can be effectively reduced. This suggests that inverting soil layer parameters using measured values from working conditions is a feasible method for dynamically predicting the excavation process of the pit. The research results have some reference value for the selection of soil layer parameters in similar areas.

Numerical simulation of local scour around an inclined monopile in steady current

Local scour around the underwater supports of constructions would reduce the embedment depth and bearing capacity of support structures, seriously threatening the safety of the structures. Most existing investigations focused on the local scour of a vertical pile. However, in practical engineering, inclined piles are widely applied in underwater foundation structures to withstand lateral loads. The pile inclination can result in flow field alteration around the pile, thereby affecting the development of local scour. Consequently, a threedimensional numerical model of local scour around an inclined pile under steady current is established using the open-source CFD package OpenFOAM, in which the hydrodynamics are solved based on the Reynolds-averaged Navier-Stokes (RANS) equations together with k – ω SST turbulence closure in this model. It is then coupled with both bed load and suspended load transport descriptions, which drive the resultant morphology of the bed. The numerical model is verified by comparing it with the existing laboratory experiment. Discussions are carried out on the effects of inclination angles on the flow field alteration and the local scour depth variation.

Effects of dynamic load application, irregular wave conditions, and base flexibility on the structural response of a vertical pile platform

The dynamic structural response of a vertical pile port platform under the action of irregular wave loads considering soil-structure interaction is studied. Deck displacement and bending moment on the piles were evaluated for a set of structural, hydraulic, and geotechnical parameters. Static structural analyses with the maximum base shear produced by wave loads and dynamic time-history analyses are performed to study the effects of dynamic amplification on the structural response of the platform. Two types of waves are analyzed, regular and irregular, to analyze the amplification effects due to the superposition of a wave train of different periods in the case of irregular waves. Cases with fixed base support and non-linear spring-modeled soil are considered to evaluate the effect of considering a flexible base for the platform. Eight structures composed of a different number of piles and with different heights were analyzed. Six wave conditions with different characteristics are used, varying the wave period and mean water height. Two sandy and two clayey soil profiles are considered with different densities and consistency. The results show that resonance effects associated with dynamic loading and small-period wave superposition in cases of irregular waves significantly affect the response. Furthermore, considering a flexible base tends to decrease the response for short wave periods, concluding that, in most cases, for wave periods close to 5 s, considering a fixed base model overestimates the response.

Nonlinear Analysis of Bearing Characteristics of Stiffened Deep Cement Mixing Piles under Vertical Loading

Stiffened deep cement mixing (SDCM) piles are composite piles that combine the advantages of single large-diameter deep cement mixing (DCM) and precast concrete piles. They comprise precast concrete piles as the core and cast-in-place DCM piles as the outer layer. This study evaluates the bearing characteristics of SDCM piles under vertical loading. The composite modulus of elasticity of SDCM piles is first introduced and determined using the area-weighted average method. Then, the reliability of the proposed method is described by comparing the calculated results with the findings of the existing literature. Furthermore, a nonlinear simplified analysis method based on the load transfer method is proposed for vertical bearing characteristics of equal- and short-core SDCM piles under vertical loading. This method is developed by the finite difference method. The accuracy of the simplified method is validated by comparing its results with those from existing tests, theoretical analysis, and finite element simulations. The results of their study indicated that the area-weighted average method calculates the composite modulus of elasticity of the composite pile section of the SDCM piles with an error below 0.5% compared to the analytical method. This finding represents sufficient accuracy. The simplified calculation method established in this study is computationally stable. When the iteration factor is set to 10−6, as the number of discrete nodes n on the pile increases, the calculation results are stable with a good convergence when n > 30. The vertical bearing capacity and pile top stiffness of SDCM piles increased with the length of the core piles. There was a reasonable core-to-length ratio for SDCM piles in specific scenarios. An excessively long DCM pile section made its lower part force-free for a given length of core piles. The appropriate length of core piles should be determined in actual projects to avoid unnecessary material waste. An optimum ratio of core piles for SDCM piles was determined. Beyond this optimal value, an increase in the ratio of core piles controlled the pile settlement in a limited manner.

Experimental and numerical study of laterally loaded vertical and batter piles in sandy soil conditions

Experimental and numerical study of laterally loaded vertical and batter piles in sandy soil conditions

Reliability updating for lateral failure of historic quay walls

ABSTRACT The historic canal walls of Amsterdam, stretching 200 km in total, are constructed as a masonry wall on a timber deck supported by vertical timber piles. Understanding the resistance against lateral failure of these quays has been challenging due to uncertainties in their working principles, geometry, soil and structural properties. This paper proposes a Bayesian approach to include evidence from past loading situations and corresponding deformations into the reliability assessment. This approach enables refinement of the reliability predictions and parameter distribution uncertainties, leading to a more accurate prediction of the resistance against the lateral failure of historic quay wall. Depending on the type of evidence, an a-priori reliability prediction for a quay wall that fails to meet safety standards can be updated to any of the three consequence classes outlined in NEN8700. In a case study, a quay wall with an a-priori reliability of β = 1.5 has been increased to β = 3.2 by including evidence of an extreme survived load of 10 kN/m2 that resulted in displacements of less than 4 mm. This is a decrease in failure probability by two orders of magnitude, showing the potential impact of using observational information in combination with Bayesian updating.

Response of vertical and batter piles under combined lateral and vertical loading conditions in sandy soil

Response of vertical and batter piles under combined lateral and vertical loading conditions in sandy soil

Numerical solution for the laterally loaded rigid piles considering resisting force and moment under combined loadings

A numerical method is first proposed for the response of laterally loaded rigid piles under lateral load based on the curved strain wedge model. The influence of shear displacement of the pile, resistance bending moment caused by the uneven vertical shear stress on the pile side and resistance force and bending moment at the pile bottom are all considered. The effect of the vertical load on the lateral response of the monopile foundation is then analyzed according to the practical fact that the piles are always subjected to combined loads. The vertical friction force on the pile side is derived by combining vertical load and horizontal bending of the pile, and the resistance force at the pile bottom is determined by both vertical load and pile self–weight. The effect of P–Δ on the pile foundation caused by the vertical load is also considered. Several field tests are used to verify the reasonableness and accuracy of the proposed method. The influencing factors are studied. The results show that the vertical load has a favorable effect on the lateral response of the pile in frictional soil and almost no effect on the lateral response of the pile in frictionless soil.

Hydrodynamic Performance of an Array of Stratified Pile Rock Breakwaters Placed on Elevated Seabed

Abstract The present study outlines the hydrodynamic performance of stratified pile-rock breakwaters (SPRBs) in series using the analytical calculation under the framework of linearized potential flow theory. The rubble mounds are separated into two porous layers (surface and bottom layers) and tightly packed within the space available between the seaside and leeside vertical piles. The SPRB is installed on the elevated bed, and it is considered as a bottom rigid layer. The newly proposed breakwater is titled as stratified pile-rock breakwater and vertical piles are suggested to minimize the unwanted displacements of rubble mounds from frequent failures due to the incident wave stroke. The analytical model is developed based on the method of matched eigenfunction expansions (MMEEs) along with suitable boundary conditions to assess the hydrodynamic performance of the SPRB. The study results are compared with the literature based on experimental and analytical methods for specific conditions. The wave reflection, transmission, and energy damping by a series of SPRBs are reported for changes in incident wave properties and breakwater physical properties. The effect of layer porosity, angle of contact, free spacing, and number of breakwaters on the hydrodynamic coefficients is reported. The study suggested that a pair of SPRBs having 80% and 40% porosities for surface and bottom layers, with clear spacing, varied within 1 ≤ w/h1 ≤ 2, and the angle of contact varied within 30 deg ≤ θ ≤ 45 deg to achieve a 90% wave-damping when the relative wavenumber is k10h1 = 1.

SUBSTANTIATION OF CONCEPTS OF SUBGRADE’S STRENTHENING IN UKRAINE AND THE EUROPEAN UNION

Purpose. Substantiating the concepts of subgrade’s strengthening in Ukraine and the European Union. In the work, based on the experience gained in the field of increasing the strength and stability of objects constructed from the soil, based on the ranking of parameters, the hypothesis about the greatest effectiveness of vertical strengthening elements, unlike all others, in the case of transition to a combined track (1520/1435 mm) is proven. Methodology. The options for strengthening the subgrade with geotextile or geogrid, as well as a rigid layer, are considered, as regulated by CP-0204 "Rules for the arrangement of the main subgrade site during major repair and modernization of the track". Three concepts of strengthening developed and implemented in the European Union with the help of: 1) geosynthetic materials; 2) vertical piles or micropiles; 3) combinations of geosynthetic materials with piles (Geosynthetic-Reinforced-Pile-Supported) are analyzed. Findings. The ranking of the methods of strengthening the subgrade was carried out according to positive and negative parameters that characterize the situation of placement of reinforcement elements in the soil matrix. Reinforcement parameters are divided into positive (reduction of horizontal and vertical deformations) and negative (technology parameters). It was determined that the maximum value of the positive impact on the reduction of vertical deformations is provided by options of vertical piles or micropiles created on the basis of Boring and Mixing Technology or Jet-grouting. Originality. For the first time, on the basis of the ranking formulas for positive and negative parameters, the justification of the concepts of subgrade’s strengthening in Ukraine and the European Union was performed. Practical value. Any method of strengthening can be ranked before its practical implementation. That is, its efficiency and rationality can be determined during implementation in specific situations of railway operation, with subgrade that needs strengthening.

SUBSTANTIATING THE CONCEPTS OF COMPONENTS COMPOSITION AND METHOD OF OBTAINING SOIL-CEMENT ELEMENT FOR REINFORCEMENT OF EMBANKMENTS

Purpose. Substantiating of the choice of components of materials and methods of obtaining a soil-cement element for strengthening the ground bases in Ukraine, taking into account the European experience. Methodology. The concepts of embankment reinforcement developed and implemented in Ukraine and the European union using horizontal reinforcement (geosynthetic materials), vertical reinforcement (vertical piles or micropiles) and a combination of geosynthetic materials with piles are analyzed. Advantages and disadvantages of physic-chemical and mechanical strengthening methods are considered. Findings. The substantiation of the material and constituent components of soil-cement elements and methods of their creation for strengthening the embankment of railways was carried out. One of the effective directions for obtaining vertical reinforcing elements and reducing the cost of work on strengthening and strengthening the embankment is the use of a mixture of soil with the addition of cement, obtained by drilling mixing technology. To modify the structure of soil cement and minimize cement consumption, it is suggested to use fiber fibers, chemical additives and finely dispersed industrial waste in the form of ash or ground slag as reinforcing components. A study was conducted to establish the basic parameters of the soil-cement composition for further modification of the structure of the element under the specific situational conditions of the embankment. Originality. The originality of the work is that, for the first time, based on the strengthening experience, the justification of the directions of strengthening the ground bases with vertical soil-cement elements at different stress-deformation conditions of the soil foundations and the composition of vertical elements in Ukraine and the European union was performed. Practical value. The practical value of the presented research is that when choosing one or another method of strengthening soil bases, the appropriate composition of the strengthening material is selected, that is, its efficiency and rationality can be determined during implementation in the specific conditions of operation of the railway, the embankment of which needs to be strengthened or rearranged for a combined or European track.

Study on the dynamic characteristics of pile wharves subjected to underwater explosion

A test was conducted to investigate the dynamic response characteristics and damage modes of pile wharves subjected to underwater explosions. To simulate the explosion process, a fluid-solid coupling finite element model of the pile wharf was constructed. The structural damage process, response characteristics, and failure modes of the pile wharf were analyzed based on the experimental and numerical simulation results. The results showed that the main damaged components of the pile wharf were the piles, with damage modes of cracks, spalling, and brittle shear. The probability of moderate or more significant damage to the inclined piles was 25% higher than that of the vertical piles. The inclined piles with low deformation ability were more prone to local concrete brittle failure, significantly increasing the possibility of instability and failure of the pile wharf structure. The acceleration response spectrum indicated that although the structure of the pile wharf was severely damaged, the personnel on its surface slab still had a high probability of survival. The study indicates that replacing inclined piles with alternative optimized structures benefits the blast resistance of pile wharves.

Variance reduction function for a potential inclined slip line in a spatially variable soil

Variance reduction function for a spatially variable soil property is an important factor that affects the spatial average-based characteristic value, which in turn influences the design of a geotechnical structure in the context of Eurocode 7. This study derives the theoretical and approximate variance reduction functions (VRFs) for a potential inclined slip line in a spatially variable soil. Only stationary random fields are studied but more general spatial variability characteristics including smoothness and hole effect are considered. First, the closed-form one-dimensional (1D) VRFs are investigated, including the VRFs for classical one-parameter autocorrelation models, the non-classical two-parameter Whittle-Matérn (WM) model, and the most general three-parameter cosine Whittle-Matérn (CosWM) model proposed to date. It is found that closed-form solutions are not available or not practical to compute in general and the simple approximate VRF (equal to scale of fluctuation/averaging length) is not adequate for the non-classical autocorrelation models (WM and CosWM). Two approximate VRFs are developed in this study for the 1D WM and 1D CosWM models. For a spatial average over an inclined line, this paper derives the theoretical scales of fluctuation (SOFs) and VRFs for five commonly used 2D autocorrelation models. The theoretical solutions show that the equivalent SOFs proposed in the literature are only applicable under special conditions which are clarified in this paper. More general approximations for the VRF over an inclined line are proposed. The range of applicability for each approximation is stated. The proposed approximate VRFs are shown to be reasonably accurate when they are applied to the spatial average-based characteristic value and for the design of a vertical pile and an inclined soil nail.

Performance of vertical and batter pile groups under vertical vibrations: a comparative assessment using model-scale field testing and numerical study

Performance of vertical and batter pile groups under vertical vibrations: a comparative assessment using model-scale field testing and numerical study